The subject matter disclosed herein relates to a transition nozzle and, more particularly, a transition nozzle having non-axisymetric endwall contouring.
Typical gas turbine engines include a compressor, a combustor and a turbine. The compressor compresses inlet gas and includes and outlet. The combustor is coupled to the outlet of the compressor and is thereby receptive of the compressed inlet gas. The combustor then mixes the compressed gas with combustible materials, such as fuel, and combusts the mixture to produce high energy and high temperature fluids. These high energy and temperature fluids are directed to a turbine for power and electricity generation.
Generally, the combustor and the turbine would be aligned with the engine centerline. A first stage of the turbine would thus be provided as a nozzle (i.e., the stage 1 nozzle) having airfoils that are oriented and configured to direct the flow of the high energy and high temperature fluids tangentially so that the tangentially directed fluids aerodynamically interact with and induce rotation of the first bucket stage of the turbine.
With such construction, the first turbine stages exhibit strong secondary flows in which the high energy and high temperature fluids flow in a direction transverse to the main flow direction. That is, if the main flow direction is presumed to be axial, the secondary flows propagate circumferentially or radially. This can negatively impact the stage efficiency and has led to development of non-axisymetric endwall contouring (EWC), which has been effective in reducing secondary flow losses for turbines. Current EWC is, however, only geared toward conventional vanes and blades with leading and trailing edges.